John Travolta has a lace front weave. his hair system seems quite complicated.

"Some of the finer hair systems are created with a fine mesh material which then has hairs attached to the mesh, put together a hair at a time. At the hairline, a transparent plastic type material is used to match the skin tones and it is attached (glued) to the skin. For the mesh part behind the leading hairline edge, the hairs are layered so that the fine mesh does not show. The transition from front to back of the system must be meticulously put together."

He's famous for battling mythic Egyptian mummies on the big screen, but in real life Brendan Fraser has been fighting a different kind of curse - male pattern baldness.
The 38-year-old actor appears to have gone to rather extraordinary lengths to regain his once full head of tousled brown hair.
Hair raising: Brendan Fraser's hair was thinning severely in 2003; yesterday he stepped out in Shanghai with a full crown

It was clear in 2003 that the one time pin-up was thinning rapidly, but as he wrapped filming the third instalment of the Mummy franchise in Shanghai yesterday, his long mane had made a rather miraculous comeback.
Perhaps it's courtesy of a hair transplant or an old fashioned toupee, but whatever the case, he looked to be rather pleased with the result, giving fans a thumbs up as he left the studio.
source: dailymail

UK TV presenter Gail Porter lost her hair in 2005 through inexplicable alopecia, and only recently has it started to grow back. She has spoken openly about having the condition and has never shied away from appearing in public with her bald head (dailymail.co.uk):

Everyone in Hollywood has fake hair.They all wear hair extensions,wigs,weaves.
But i can't believe someone like Beyonce is a spokesperson for L'Oreal hair products because we have NEVER seen her real hair..
She always wears weaves.